[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220600
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN DEC 22 2013

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

GALE FORCE WINDS ARE OCCURRING ACROSS PORTIONS OF THE SW
CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA...FROM 11N-13N
BETWEEN 74W-78W...UNTIL 22/1200 UTC. THE WINDS ARE DUE TO A
STRONG PRESSURE GRADIENT BETWEEN A 1034 MB HIGH CENTERED OVER
THE NORTH CENTRAL ATLANTIC NEAR 35N53W AND A 1004 MB LOW
CENTERED OVER NORTH COLOMBIA NEAR 6N74W.

A COLD FRONT EXTENDING FROM LAKE CHARLES LOUISIANA TO JUST S OF
BROWNSVILLE TEXAS WILL SWEEP SE AND BE REINFORCED BY A
SECONDARY SURGE OF COLD AIR. THIS SECONDARY SURGE OF COLD AIR
WILL RESULT IN GALE FORCE WINDS BY LATE MON OVER THE SW GULF S
OF 22N W OF 92W.

FOR BOTH GALE AREAS...PLEASE REFER TO THE LATEST NHC/TAFB HIGH
SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR
MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 6N10W TO 4N25W TO 4N40W TO THE COAST OF SOUTH AMERICA
NEAR 3N51W. ISOLATED MODERATE CONVECTION WAS INDICATED WITHIN
60-120 NM N OF THE ITCZ BETWEEN 23W-40W.

...DISCUSSION...

GULF OF MEXICO...

AS OF 0300 UTC...A COLD FRONT EXTENDED FROM LAKE CHARLES
LOUISIANA TO JUST S OF BROWNSVILLE TEXAS. GALE FORCE WINDS WERE
OCCURRING E OF THE FRONT HAVE NOW DIMINISHED TO 20 TO 30 KT.
COASTAL WSR-88D IMAGERY SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE OCCURRING ALONG AND WITHIN 120 NM NW OF THE
FRONTAL BOUNDARY ALONG THE TEXAS AND LOUISIANA COASTS IN AN
OVERRUNNING PATTERN. S TO SW RETURN AHEAD OF THE FRONT HAS NOW
DIMINISHED TO 20 TO 30 KT NEAR THE FRONT. THE WINDS ELSEWHERE E
OF THE FRONT WERE GENERALLY FROM SE TO S AT 15 TO LOCALLY 25 KT.
THERE WERE REPORTS OF LOW CEILINGS AND FOG OUTSIDE OF CONVECTIVE
ACTIVITY OVER THE NE GULF AHEAD OF THE FRONT. FAIR WEATHER IS
OVER THE REMAINDER OF THE GULF E OF FRONT. IN THE UPPER
LEVELS...SW FLOW ON THE BACKSIDE OF AN UPPER LEVEL ANTICYCLONE
NEAR 26N75W AND ASSOCIATED RIDGE WAS ADVECTING MID TO UPPER
LEVEL MOISTURE OVER THE E GULF AND WITHIN A NARROW BAND OVER
LOUISIANA. SOME SUBSIDENCE WAS OVER THE REMAINDER OF THE GULF.
THE COLD FRONT IS FORECAST TO SWEEP EASTWARD AND EXTEND FROM
THE FLORIDA PANHANDLE TO THE BAY OF CAMPECHE BY SUN NIGHT.

CARIBBEAN SEA...

GALE FORCE WINDS ARE OCCURRING ACROSS PORTIONS OF THE SW
CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA. SEE SPECIAL
FEATURES SECTION ABOVE. A 0226 UTC ASCAT PASS INDICATED A LARGE
AREA OF 20-25 KT TRADEWINDS OVER THE CARIBBEAN SEA FROM 11N TO
18N BETWEEN 65W AND 80W...WITH THE STRONGEST WINDS OCCURRING JUST
S OF HISPANIOLA AND NEAR THE WINDWARD PASSAGE. SCATTERED WARM
TOP SHOWERS ARE OVER THE GULF OF HONDURAS...BELIZE...
GUATEMALA...HONDURAS...NICARAGUA...AND COSTA RICA. ADDITIONAL
ACTIVITY WAS FOCUSED OVER E CUBA...JAMAICA...HISPANIOLA...
PUERTO RICO...THE LEEWARD ISLANDS...AND THE WINDWARD ISLANDS.
THE UPPER LEVELS...A CLOSED ANTICYCLONE NEAR 26N75W WAS
PROVIDING A LOW-LATITUDE REX BLOCKING PATTERN OVER THE CARIBBEAN
AND WRN ATLANTIC WITH AN ATTENDANT TROUGH AXIS EXTENDING FROM
THE TROPICAL ATLC WESTWARD ACROSS THE NORTHERN LEEWARD
ISLANDS...PUERTO RICO...HISPANIOLA TO E CUBA. VERY STRONG
SUBSIDENCE WAS NOTED WITHIN 180-240 NM OF THE TROUGH AXIS.  THE
BLOCKING PATTERN OVER THE CARIBBEAN IS EXPECTED TO PERSIST OVER
THE NEXT 24 HOURS...AND PERHAPS AMPLIFY BEYOND AS AN UPPER LOW
IS EXPECTED TO CLOSE OFF OVER PUERTO RICO BY LATE MON.

...HISPANIOLA...

SCATTERED LOW TOPPED SHOWERS ARE OVER THE HIGHER ELEVATIONS OF
HISPANIOLA MOVING W WITHIN FRESH TRADEWIND FLOW. CONDITIONS
REMAIN CAPPED DESPITE THE PRESENCE OF AN UPPER LEVEL TROUGH
LYING ACROSS THE AREA. THE VERY STRONG SUBSIDENCE ALOFT WAS
CAPTURED BY VERY DRY AIR ABOVE 650 MB IN THE 00Z SAN JUAN RAOB.
LITTLE CHANGE IN THIS SCENARIO IS EXPECTED OVER THE NEXT 24
HOURS.

ATLANTIC OCEAN...

A 1034 MB HIGH IS CENTERED NE OF BERMUDA NEAR 35N53W IS
PRODUCING FAIR WEATHER OVER THE BAHAMAS AND W ATLANTIC. ANOTHER
1034 MB HIGH IS CENTERED OVER THE E ATLANTIC NEAR 35N16W. A
SURFACE TROUGH IS OVER THE CENTRAL ATLANTIC FROM 30N37W TO
22N40W. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE TROUGH.
ANOTHER SURFACE TROUGH IS OVER THE TROPICAL ATLANTIC FROM 20N50W
TO 10N46W MOVING W. SCATTERED SHOWERS ARE WITHIN 180 NM OF THE
TROUGH AXIS. OF NOTE IN THE UPPER LEVELS...A LARGE UPPER LEVEL
LOW IS CENTERED OVER THE E ATLANTIC NEAR 28N31W. SCATTERED
SHOWERS ARE FROM 18N-33N BETWEEN 16W-26W TO INCLUDE THE CANARY
ISLANDS.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
COBB


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